Many known fluorescent lamps utilize a low-pressure buffered mercury discharge to produce ultraviolet light, which is converted to visible light by a phosphor coating. Mercury vapor is generally required for the successful and efficient operation of many conventional fluorescent lamps. However, for enhanced environmental compliance, there are steady efforts to reduce the amount of mercury per lamp. Some new lamp designs may require performance under the constraint of mercury levels in the range of about 1 mg or less per lamp. To achieve this, it is important to ensure that lamp components perform with minimal reactions with the mercury in the gaseous fill, in order to reduce binding of mercury with other components of the lamp. Such may result in premature lamp failure. Typically, lamp electrodes may act as sites for mercury binding due to interactions between mercury and the electrode components. Furthermore, electrodes may suffer sputtering of their emissive mixture to form deposits on the interior of a lamp envelope during lamp operation, which deposits may bind additional mercury.
The electrode of fluorescent lamps operating on alternating current act alternative in an anode and a cathode mode. Owing to anode current passage to the electrode lead wires in fluorescent lamps, the following may occur: end discoloration, mercury loss, and lamp failure. This can be problematic, especially with an increased emphasis on longer life specification and lower mercury content in lamps.
It remains desirable to develop and implement low pressure discharge lamps which overcome the problems noted above.